Cache: other uses

Other uses of cache principle

Multiple levels

Pentium III

L1 cache: 16K

L2 cache: 512K

Disk cache: keep file data blocks in memory

Web cache: keep web pages on:

local hard drive

local server

Virtual memory

Extend memory hierarchy beyond RAM to disk

How big is 32-bit address space (number of valid addresses)?

Do most systems have that much memory?

Do programmers want to use as much memory as possible?

Solution: use RAM as a cache for data blocks on disk

Advantages

Single program can use very large address space

Multiple programs can share same physical memory

Memory access can be protected between programs